1. Field of the Invention
The invention relates to a multi-chip image sensor module, and in particular to an image sensor module having the improved quality and the reduced volume.
2. Description of the Related Art
Referring to FIG. 1, a conventional image sensor module includes a lens holder 10, a lens barrel 20, and an image sensor 30. The lens holder 10 has an upper end face 12, a lower end face 14 and an opening 16 penetrating through the lens holder 10 from the upper end face 12 to the lower end face 14. An internal thread 18 is formed on an inner wall of the opening 16 of the lens holder 10. The lens barrel 20 formed with an external thread 22 is inserted from the upper end face 12 of the lens holder 10, received within the opening 16, and screwed to the internal thread 18 of the lens holder 10. The lens barrel 20 is formed with a transparent region 24 under which an aspheric lens 26 and an infrared filter 28 are arranged in sequence. The image sensor 30 has a first surface 32 and a second surface 34 opposite to the first surface 32 on which a transparent layer 36 is arranged. The image sensor 30 is bonded to the lower end face 14 of the lens holder 10 through the transparent layer 36. The screwed length between the lens barrel 20 and the lens holder 10 may be adjusted to control the distance from the aspheric lens 26 of the lens barrel 20 to the transparent layer 36 of the image sensor 30.
The above-mentioned image sensor module has the following drawbacks.
1. Because the image sensor 30 is bonded to the lower end face 14 of the lens holder 10 through the transparent layer 36, the image sensor 30 cannot be replaced when the image sensor 30 of the module is damaged. In this case, the overall module has to be treated as a waste material, and other good elements in the module may not be recycled.
2. Because the transparent layer 36 is bonded to the lower end face 14 of the lens holder 10 by the adhesive, which may contaminate the surface of the transparent layer 36, poor optical signals may be obtained.
3. When the module is assembled, the transparent layer 36 has to be precisely positioned with the aspheric lens 26 and then bonded to the lens barrel 20. Once the positional precision deviates from the standard level, the overall module cannot be reassembled and has to be treated as the waste material
4. The lens holder 10 has to be additionally provided to combine the lens barrel 20 with the image sensor 30.